Box-type and cylindrical culvert constructions are known, in which the main culvert portion provides a bottom wall, side walls and a top wall for a generally-crosswise passage (such as a stream passage or path or roadway) under an embankment which extends along a longitudinal axis (e.g., of a road on top of the embankment). Such embankments normally have a laterally outwardly and downwardly inclined fill slope at each side, through which some sort of portal construction is adapted to project from one end of the main culvert body. Such a fill slope defines a fill slope plane with a desired vertical fill slope angle, as measured in a vertical plane perpendicular to the longitudinal embankment axis.
In prior culvert arrangements in which the culvert defines a passage extending transversely through the embankment in a vertical plane perpendicular to the longitudinal embankment axis, portal constructions are known, as shown in Hewett U.S. Pat. No. 1,144,200, and in Odendahl U.S. Pat. No. 2,263,588, for use with a main culvert body portion which includes a series of individual tubular or box-like sections assembled in end-to-end relationship to each other to define the desired main culvert passage. The precast portal members of such patents provide continuing bottom and side wall portions for direct connection at one end of the culvert. In these cases, the upper edges of the portal side walls extend symmetrically outwardly and downwardly from the culvert end at identical vertical angles which fit the desired fill slope plane. In such prior patents the side walls also flare symmetrically outwardly with reference to such a transverse vertical plane perpendicular to the longitudinal embankment axis. In another previously-known type of portal assembly, a precast portal end section, for direct connection at one end of such a main culvert passage extending perpendicularly across such an embankment axis, has been provided with a bottom wall and integral side walls which extend symmetrically away from the culvert end in vertical planes parallel to each other and also perpendicular to the embankment axis.
There is a problem, however, in providing a portal construction at the outer end of a culvert, when the culvert extends crosswise through the embankment at an acute skew angle with respect to such a transverse vertical plane. For example, if a symmetrical portal section of the type shown in the above patents is attached directly as a normal extension at one end of such a skewed culvert, the respective upper edges of the side walls would not both match the fill slope plane.
In prior constructions, it has accordingly been customary to construct molding forms for such a portal section on the site of culvert installation, and to form individual portal side walls on the site, where the upper edges of such forms can be constructed unsymmetrically to individually match the desired fill slope plane. In such cases, such side walls have been cast as separate wings of such a portal, either on top of a previous on-site casting for a portal base, or with subsequent on-site casting of such a portal base portion in between the on-site castings for the individual side walls or wings of the portal.
Such on-site construction of portals makes it necessary to have skilled personnel crews at the site to make the necessary forms, and successively cast and finish the various elements of such a portal. Such operations accordingly involve extra cost and time, particularly when it is necessary to use such construction methods for on-site construction of portals for individual culverts which may extend through their respective embankments at a variety of different skew angles, corresponding to the different original directions of the stream or other type of passage involved.
Some efforts have been made to provide preconstructed molds or forms to expedite the casting of culvert walls and/or portal portions, as shown for example by DeLaMare U.S. Pat. Nos. 1,461,973 and 1,560,811, Scott 1,926,633, Odendahl 2,247,517, Holland 3,696,177 and Cast 3,826,460. Some of these prior mold forms are useful only for on-site casting of upper culvert bodies on top of a culvert bottom wall previously poured at such site. None of them provides forms or methods for possible precasting of different portal members which could be used satisfactorily at an outer end of a culvert which extends through its embankment at a skew angle or which could be used satisfactorily for selectively precasting portal members of different shapes for use at the ends of culverts with different skew angles.